Fueling system vapor recovery and containment performance monitor and method of operation thereof

• US 6,968,868 B2
• Filed: 12/11/2003
• Issued: 11/29/2005
• Est. Priority Date: 11/30/1999
• Status: Expired due to Term

• Current Assignee: Veeder-Root Co (Vontier Corp.)
• Original Assignee: Veeder-Root Co (Vontier Corp.)
• Inventors: Hart, Robert P., Lucas, Richard K.
• Primary Examiner(s): MAUST, TIMOTHY LEWIS
• Application Number:
  US10/733,480
• Publication Number:
  US 20040154692A1
• Time in Patent Office: 719 Days
• Field of Search: 141 2- 8, 141/44, 141/45, 141/59, 141/83, 141 94- 96, 141/206, 141/209, 141/302, 73/12.5, 73/12.6, 73/13.4, 73/13.6, 73/14.9, 73/491, 73/495, 73/497
• US Class Current: 141/6
• CPC Class Codes: B67D 7/0486 Pumps driven in response to electric signals indicative of pressure, temperature or liquid flow
• CPC Class Codes: B67D 7/0496 Performance test devices therefor
• CPC Class Codes: F02M 25/0809 Judging failure of purge control system
• CPC Class Codes: F02M 25/0872 Details of the fuel vapour pipes or conduits
• CPC Class Codes: G01M 3/02 by using fluid or vacuum
• CPC Class Codes: G01M 3/26 by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors

Abstract

A method and apparatus for monitoring and determining fuel vapor recovery performance. The dispensing of liquid fuel into a tank by a gas pump nozzle displaces a mixture of air and fuel ullage vapor in the tank. These displaced vapors may be recovered at the dispensing point nozzle by a vapor recovery system. A properly functioning vapor recovery system recovers approximately one unit volume of vapor for every unit volume of dispensed liquid fuel. The ratio of recovered vapor to dispensed fuel is termed the A/L ratio, which should ideally be approximately equal to one (1). The A/L ratio, and thus the proper functioning of the vapor recovery system, may be determined by measuring liquid fuel flow and return vapor flow using a vapor flow sensor on a nozzle-by-nozzle basis. The determination of A/L ratios for individual nozzles are calculated using a reduced number of vapor flow sensors.

Claims

1. A method of monitoring a vapor recovery system that recovers vapors expelled from a vehicle during refueling and returns the vapors back to an underground storage tank in a service station environment, comprising:

a measuring an amount of fuel flow delivered to the vehicle at a plurality of fuel dispensing points;

measuring amounts of vapor flow recovered at said plurality of fuel dispensing points to be returned back to the underground storage tank in aggregate from active fuel dispensing points in said plurality of fuel dispensing points using at least one vapor flow sensor wherein the number of said at least one vapor flow sensors is less than the number of said plurality of fuel dispensing points that can be active at any one time; and

determining an estimate of the amount of vapor flow recovered by each of said plurality of fuel dispensing points using said amounts of vapor flow recovered in aggregate from said active fuel dispensing points in said plurality of fuel dispensing points.

2. The method of claim 1, wherein said step of determining is performed by a central electronic control.

3. The method of claim 1, wherein of claim said step of measuring amounts of vapor flow is performed in a vapor return pipeline common to all of said plurality of fuel dispensing points.

4. The method of claim 1, wherein said step of measuring amounts of vapor flow is performed in a vapor return passage.

5. The method of claim 1, wherein said step of measuring the amount flow is performed by receiving information from meters that measure the amount of fuel flow for each of said plurality of fuel dispensing points.

6. The method of claim 1, wherein said vapor flow is recovered in a vapor return path, and further comprising determining if said vapor flow is present in said vapor return path when none of said plurality of fuel dispensing points are active to determine if the vapor return path has failed.

7. The method of claim 1, further comprising the steps of:

monitoring a pressure level in the underground storage tank; and

selectively drawing a negative pressure into underground storage tank fuel when said pressure level is above a desired threshold pressure value.

8. The method of claim 1, further comprising the steps of:

identifying the start of an idle period for each of said plurality of fuel dispensing points;

determining whether pressure in the underground storage tank is equal to or below a minimum level;

selectively adjusting pressure in the underground storage tank to a preset lower level when the previously determined pressure is above the minimum level;

monitoring variation of the pressure in the underground storage tank during the remainder of the idle period;

determining the end of said idle period; and

determining the acceptability of vapor containment in the underground storage tank based on the variation of said pressure during said idle period.

9. The method of claim 1, further comprising registering a leak in a fuel dispensing point in a group of said plurality of fuel dispensing points, wherein said group shares a common vapor flow sensor, if said common vapor flow sensor registers a reverse vapor flow when said group of said plurality of fuel dispensing points is idle.

10. The method of claim 1, further comprising determining a ratio of vapor flow to fuel flow for each of said plurality of fuel dispensing points by dividing said amounts of vapor flow recovered at a dispensing point in said plurality of fuel dispensing points by said amount of fuel flow delivered at a dispensing point in each of said plurality of fuel dispensing points.

11. The method of claim 10, further comprising the step of generating a signal when said ratio of vapor flow to fuel flow is not within an acceptable range.

12. The method of claim 10, further comprising the step of deactivating any of said plurality of fuel dispensing points whose ratio of vapor flow to fuel flow is determined to not be within an acceptable range.

13. The method of claim 10, further comprising the step of recording the measurements of said ratios of vapor flow to fuel flow in a memory.

14. The method of claim 10, wherein said step of determining a ratio is performed when only one of said plurality of fuel dispensing points is active.

15. The method of claim 14, wherein said step of determining a ratio is performed after each of said plurality of fuel dispensing points are idle.

16. The method of claim 15, wherein said step of determining a ratio further comprises determining when said plurality of fuel dispensing points are idle by either monitoring a dispenser loop or the fuel level in the underground storage tank.

17. The method of claim 10, wherein said step of determining a ratio comprises:

forming a generalized equation for the relationship between vapor flow, fuel flow, and the ratio of vapor flow to fuel flow, for each active fuel dispensing point in said plurality of fuel dispensing points; and

solving each of said generalized equations for said ratio of fuel flow to vapor flow for all active said plurality of fuel dispensing points.

18. The method of claim 17, wherein said generalized equation is in the form of R=(L^TL)⁻

1L^TA.

19. The method claim 10, further comprising determining if a fuel dispensing point in a group of said plurality of fuel dispensing points, wherein said group share a common vapor flow sensor, has a failure, comprising the steps of:

performing said step of determining said ratio of vapor flow to fuel flow for each of said fuel dispensing points in said group;

determining which of said vapor flow to fuel flow ratios in said group are below a preset minimum; and

determining which of said vapor flow to fuel flow ratios in said group do not lower in value.

20. The method of claim 10, further comprising determining if a fuel dispensing point has a leak, comprising the steps of:

determining which of said ratios of vapor flow to fuel flow for each of said plurality of fuel dispensing points are below a preset minimum;

determining the average number of said ratios of vapor flow to fuel flow for each of said plurality of fuel dispensing points below said preset minimum; and

comparing the number of said ratios of vapor flow to fuel flow below the preset minimum for each of said plurality of fuel dispensing points to said average number to determine if any of said plurality of fuel dispensing points has failed.

21. The method of claim 10, further comprising determining if a fuel dispensing point that services ORVR-equipped vehicles has failed, comprising the steps of:

categorizing each of said ratios of vapor flow to fuel flow as either being (1) below a preset minimum value or (2) above or equal to said preset minimum value;

comparing each of said ratios of vapor flow to fuel flow below said preset minimum value, and above or equal to same preset minimum value to respective expected values for each and determining the individual proportional differences between each of said ratios of vapor flow to fuel flow below said preset minimum value, and above or equal to same preset minimum value to said respective expected values;

combining said individual proportional differences; and

comparing said individual proportional differences to a critical threshold value to determine if one of said plurality of fuel dispensing points has a failure.

22. The method of claim 10, further comprising determining if a fuel dispensing point that services ORVR-equipped vehicles has failed, comprising the step of determining if said ratios of vapor flow to fuel flow for each of said plurality of fuel dispensing points that are below a preset minimum value are statistically different from the proportion of said ratios of vapor flow to fuel flow for all of said plurality of fuel dispensing points that are below said preset minimum value.

23. The method of claim 10, further comprising the steps of:

(a) determining at multiple times said amount of vapor flow;

(b) determining at multiple times said amount of fuel flow;

(c) performing said step of determining said ratio of vapor flow to fuel flow for each measurement in steps (a) and (b); and

(d) determining if said ratio of vapor flow to fuel flow for each of said calculations in step (c) is within an acceptable range.